JP2024016008A - Glass or glass ceramic plate comprising at least one coating arranged on one side, and method for producing the same - Google Patents

Abstract

To provide a glass or glass-ceramic plate which comprises a coating arranged on at least one side and is excellent in scratch resistance and oil resistance.SOLUTION: A glass or glass-ceramic plate 10 comprises: a glass or glass-ceramic substrate 1; and a coating 2 arranged on at least one side and comprising an organosilicon matrix and a pigment. The coating has a thickness of at least 10 μm. In an area where only the coating is arranged on the glass or glass-ceramic substrate, the coating has a scratch resistance of more than 7 N in a test according to DIN-ISO 1518-1, and an oil resistance of less than 1 determined as a chromaticity change ΔE when measured through the glass or glass-ceramic substrate.SELECTED DRAWING: Figure 1

Description

The present invention generally relates to coated glass or glass-ceramic plates that can be used, for example, as cover plates for cooking appliances. In particular, the invention relates to a glass or glass-ceramic plate comprising a coating disposed on at least one side of a glass or glass-ceramic substrate, and to a method of manufacturing the same. The coating contains an organosilicon matrix and a pigment, is scratch resistant, and has very good scratch resistance and very good oil resistance as a single layer.

Coated glass or glass-ceramic plates have already been used for many years as cover plates for cooking appliances (for example, known as "cooktops" on "stoves"). In recent years, cover plates containing glass or glass-ceramic have been developed, which include a transparent glass or glass-ceramic material and a coating applied to one side of the corresponding glass or glass-ceramic substrate to prevent the material from showing through. A film containing a membrane was developed. When the cooking appliance is installed, this type of coating faces away from the viewer or user, and is generally also referred to as a bottom coat or back coat.

These back or underside coats are exposed to various demands during assembly and operation, but because they are placed on the back or underside of the plate, they are also crucial for impact resistance, which is important during operation and use. influence Impact resistance here refers to the strength with which a plate can withstand mechanical loads from ``above'' or ``from the front.'' When using a covered plate as a cover plate for a stove, This can be visualized by placing the instrument down, sometimes roughly.

Especially in the case of low-expansion substrates, a so-called "thermal mismatch", that is, a difference in thermal expansion, can always occur between the substrate and the coating applied to this substrate. In the case of coatings with good hardness and/or scratch resistance, cracks may be induced in the substrate (e.g. by high baking temperatures and mismatches that occur when the coated substrate cools to room temperature). There is a possibility that Such cracks can reduce the mechanical durability of the substrate. Therefore, tensile stresses acting on the substrate, eg due to loads from above by objects placed on the plate, eg cooking utensils, can easily lead to malfunction of the substrate by fracture. This results in particularly good adhesion and scratch resistance, as well as sealing and cleaning properties, especially when substrates with rather low ductility themselves, such as certain glass-ceramics and glasses, are used. The use of a glass-based coating as a "backcoat" or "bottomcoat" that satisfies the other requirements on its own well has not been established.

Therefore, coatings with lower adhesion than conventional glass-based coatings are used, especially as backside or bottom coatings. For example, silicone coatings and silicone sol-gel binders have been proposed. Already for this reason, the risk of crack formation is relatively low in such coatings, since no melting reaction zones are formed as in conventional glass-based coatings. However, this has the disadvantage that the adhesion of this layer is also reduced. In order to ensure the strength of a plate covered with such a coating, it is often advantageous that the coating is porous, especially down to the base material. However, the underside or back side of the cover plate may be exposed to adhesive residue, water vapor or even oil, or, in the case of cover plates used on stoves operated with gas burners, for example, spilled food may leak through the holes in the gas burner. This porosity is particularly disadvantageous since it very often comes into contact with fluid media, such as reaching the underside of the cover plate. Another disadvantage of porous layers is that they usually have low scratch resistance. Corresponding coatings are described, for example, in DE 10 2008 031 428 A1.

For this reason, a further coating, also referred to as a "sealant", is often placed on top of the first layer, which is actually colored and visible through the substrate to the user. This second coating often has a different composition than the first coating and may require different baking conditions. Further, the first coating film and the second coating film may have different chromaticities. This is particularly undesirable when the first coating is very light colored and the second coating is very dark colored. In this case, the first coating must be applied particularly thickly, otherwise the second coating will show through the first coating slightly and the chromaticity will change. . Corresponding coatings are described, for example, in DE 10 2008 031 426 A1.

Furthermore, the combination of a coloring layer and a sealant layer implies an additional application and heat treatment step and is therefore disadvantageous both from an economic point of view and from the point of view of the CO ₂ balance of the product.

For example, EP 1 730 085 describes a plate made of glass or glass ceramic and having a colored coating on at least one area of at least one side, the coating comprising substantially carbon-free material. Plates are described that contain at least one polysiloxane resin without any additives, the coating having a filler content of 10 to 60% by volume. The disadvantage of this is that the coatings described in that patent document are essentially free of carbon, since in such a manner a coating with sufficient sealing properties, in particular with regard to resistance to the passage of oil, cannot be obtained. This is because a film cannot be obtained.

WO 2005/092810 describes a method for increasing the strength of glass or glass-ceramic plates. Pigmented coatings with high resistance to the passage of oil are not described.

Japanese Translation of PCT Publication No. 2011/216457 describes a plate including a glass or glass-ceramic substrate, the plate having a bottom coat including a different coating film. In particular, when the colored coating film 3 has a different configuration from the heat-resistant resin layer 4 and is further coated with another resin layer 5 that further improves the performance of the first resin layer 4. There is. The plates described therefore have a very complex layer structure, for example processes such as sputtering or even glass-based coatings may be used.

Japanese Patent No. 6,231,066 describes an article of manufacture in which a coating comprising a silicone resin with optionally branched alkyl chains is applied to a glass or glass-ceramic substrate. This method is disadvantageous since these organic components require baking at fairly high temperatures, for example at temperatures around 350°C. However, with these methods, it is not possible to produce a coating film that has both sealing properties and scratch resistance. This is because a porous layer is formed by combustion of organic components.

Japanese Patent No. 206024 also describes a coated glass plate that includes two different compositions of coatings: a decorative coating and a light-blocking coating. In addition to SiO ₂ as an essential component, the decorative coating further comprises another metal oxide, such as MnO and/or CoO.

Japanese Translation of PCT Publication No. 2019/519458 describes a coating film on a glass or glass ceramic plate that includes a silicone binder and a nanopigment. No mention is made of the scratch resistance and sealing properties of the coating.

EP 3 511 631 A1 describes a multilayer structure comprising a first decorative layer and a second heat-resistant resin layer. This layer contains pigments of very small particle size. The resin layer may be applied directly to the base material. There is no mention of the oil resistance of the coating.

EP 3 222 595 A1 describes a hob device that includes layer elements that are partially translucent. No mention is made of oil tightness and scratch resistance.

International Publication No. 2020/122069 describes a cook plate including a heat-resistant resin layer. This includes inorganic fillers in the form of flakes, especially those containing aluminum oxide. Again, no mention is made of oil resistance.

In other words, existing back-coated glass or glass-ceramic plates are demanding and costly to manufacture. Therefore, there is a need for a glass or glass-ceramic plate that at least partially alleviates the drawbacks of these prior art techniques mentioned above. There is also a need for a method of manufacturing the same.

OBJECT OF THE INVENTION The object of the invention is to provide a glass or glass-ceramic plate comprising at least one coating arranged on at least one side and a method for producing the same, which at least partially alleviates the disadvantages of the prior art. .

SUMMARY OF THE INVENTION This problem is solved by the subject matter of the independent claims. Preferred embodiments and special embodiments are the subject of the dependent claims as well as the present specification and drawings.

により与えられる。 Accordingly, the present disclosure relates to a glass or glass-ceramic plate comprising a glass or glass-ceramic substrate and a coating comprising an organosilicon matrix and a pigment, disposed on at least one side of the glass or glass-ceramic substrate. The coating has a thickness of at least 10 μm, advantageously at most 80 μm. The coating is applied to the glass or glass-ceramic plate in the areas where only the coating is arranged on the glass or glass-ceramic substrate, above 7N, preferably at most 30N, as determined by a test according to DIN ISO 1518-1. scratch resistance and a chromaticity change ΔE of less than 1, preferably less than 0.5, particularly preferably less than 0.3, very particularly preferably 0, when measured through a glass or glass-ceramic substrate. and an oil resistance of less than .2, most preferably less than 0.1, where the chromaticity change ΔE is expressed in the L ^* a ^* b ^* color system by the following formula:

is given by

Here, chromaticity 1 refers to the chromaticity of the glass or glass-ceramic plate measured through the glass or glass-ceramic substrate before loading the colored oil, and chromaticity 2 refers to the chromaticity after loading the colored oil. refers to the chromaticity of

The test is advantageously carried out as follows:
The coloring of the oil is advantageously carried out with a blue dye, for example as sold under the trade name Orasol Blue 855. This is a dye consisting entirely of a copper-phthalocyanine complex, and C.I. I. Also known as Solvent Blue 70 (CAS number 12237-24-0). To do this, first 0.5 g of powder dye is dissolved in 10 ml of isopropanol. This solution is then poured with a commercially available oil, for example sunflower oil, to make up to 50 ml.

The composition range of commercially available sunflower oils suitable for testing is listed below (see also de.wikipedia.org/wiki/Sonnenblumenoel dated May 4, 2022):

Next, prepare the test specimen. This is a specimen with minimum dimensions 80 x 80 mm ² made of coated glass or glass-ceramic plates. Advantageously, the test specimen includes only the substrate and the coating to be tested. The chromaticity of the coating is measured before loading, but through the substrate. 2 ml of an edible oil colored as described above, advantageously commercially available sunflower oil, is then applied to the coating and the sample coated with the oil thus colored is heat treated in an oven at 150° C. for 3 hours. . Thereafter, the chromaticity of the coating film is measured again through the substrate. The chromaticity was measured using a color difference meter and expressed in the CIE-L ^* a ^* b ^* color system. Next, the chromaticity change ΔE is determined from the measured values before and after loading. It is also possible, and sometimes preferred for large samples, to measure the chromaticity in untreated and oil-treated areas of the sample and determine the chromaticity change therefrom. This is possible because the heat treatment temperature of 150° C. is too low to cause any chromaticity change in the coating itself. Therefore, the chromaticity of the unprocessed portion matches the chromaticity before processing within the range of measurement accuracy. In order to eliminate the possibility of errors and artifacts, it is also possible to thermally treat the reference sample together, thereby avoiding artifacts in case of contamination of the sample, for example in the oven itself.

Overall, it may be advantageous to proceed as follows:
On the side of the plate/substrate on which the coating is arranged, a ring, advantageously made of or comprising commercially available stainless steel, advantageously having an internal diameter of 40 mm is placed. The outer diameter may be, for example, 57 mm, and it should be understood that the exact dimensions of the outer diameter are exemplary only. This ring serves in particular as a boundary to prevent uncontrolled leakage of oil. 2 ml of colored oil are then added to this ring, preferably by dropwise addition using a pipette. The ring is then covered, for example with a watch glass, to prevent rapid evaporation of the oil. The colored oil applied sample is then placed in a laboratory oven and then heated to 150°C. This temperature of 150°C is maintained for 3 hours. After the sample has cooled, the ring and cover are removed and any residual oil still present on the surface of the coating is removed, for example with a cellulose cloth.

Advantageously, the oil after heat treatment is still liquid and does not exhibit viscosity, but if it is viscous, it is assumed that the oven temperature is too high.

Next, the sample is turned over and evaluated from the base material side. First, evaluate visually. Further, chromaticity is measured using a color difference meter using the CIEL ^* a ^* b ^* color system. For this purpose, the chromaticity is measured in the untreated and treated areas of the test piece, and the chromaticity change ΔE is calculated according to the sample. Furthermore, an untreated reference sample is also advantageously recorded.

Advantageously, the chromaticity is measured using a Konica Minolta spectrophotometer, type CM700d instrument, light type D65, viewing angle of 10°. Measurement aperture MAV and measurement settings SCI can be used. Due to the high opacity of the specimen, the measurements are independent of the background, i.e. it does not matter whether the measurements are made against a black or white calibration plate.

In the scope of the present disclosure, a plate is understood to be a shaped body whose thickness is at least an order of magnitude smaller than its length and width. Furthermore, a glass or glass-ceramic plate within the scope of the present disclosure is understood to be an article of manufacture comprising a glass or glass-ceramic substrate, where the glass or glass-ceramic substrate itself is plate-shaped. In contrast to glass or glass-ceramic substrates, glass or glass-ceramic plates furthermore contain at least one coating and can therefore also be understood as processed substrates. The three-dimensional dimensions and planes of the glass or glass-ceramic substrate and the three-dimensional dimensions and planes of the glass or glass-ceramic plate approximately correspond to each other, where the thickness of the glass or glass-ceramic plate is strictly It should be noted that the thickness of the coating is greater than the thickness of the (uncoated) glass or glass-ceramic substrate. However, this is negligible within the measurement accuracy for the typical thicknesses in the mm range of glass or glass-ceramic plates/substrates considered here.

The construction of glass or glass-ceramic plates as described above has many advantages.

The coating is here constructed as a coating comprising an organosilicon matrix and a pigment and thus as a hiding or at least partially hiding coating. Hiding or at least partially hiding coatings (or layers) are understood within the scope of the present disclosure to be coatings that at least reduce the transmission of light. This is due, on the one hand, to the fact that the coating contains pigments, i.e. colored bodies, advantageously temperature-stable and/or ceramic colored bodies, which reduce the transmission of light by absorption and/or scattering. It can be considered as a thing. On the other hand, since the coating has a thickness of at least 10 μm, the hiding effect of the coating can also be attributed to its thickness. Colored bodies are understood to include within the scope of the present disclosure not only colored pigments but also effect pigments, effect pigments not necessarily being colored themselves, but for example pure silver luster pigments (e.g. the so-called (equivalent to "pearl luster pigment"). In general, these effect pigments, which do not necessarily develop color by absorption as described above, are encompassed within the scope of the present disclosure under the generic term "colored bodies."

In this way, a hiding effect can also be achieved with pigments and coatings that do not inherently have a particularly strong hiding effect, since these are, for example, transparent flake-based effect pigments (e.g. This is because the pigment is a pearlescent pigment (for example, commercially available under the trade name "Iriodin") or a coating film containing a large amount of such a pigment. Here, a high layer thickness of at least 10 μm and the favorable interaction of the pigments contained in the coating can ensure a sufficient hiding effect of the coating.

By nacreous pigments are generally understood effect pigments based on mica. In particular, the mica may be present in flake form and coated, the coating itself being a non-absorbing coating, for example a coating consisting of or comprising _TiO2 . . In this way, for example, a silvery dull luster can be achieved. It is also possible for such pearlescent pigments to contain multiple coatings, thereby creating an interference effect. In this case, for example, a specific color impression can be achieved by reflection. It is also possible to use coatings which themselves exhibit a certain specific color, for example Fe ₂ O ₃ . In this case, the pearlescent pigments obtained have a light shade, but are still not opaque absorption pigments. For example, pearlescent pigments with yellow or golden hues are known. Other shades are also possible in principle, for example purple.

Pearlescent pigments are also referred to within the scope of this disclosure as mica pigments.

The coating includes, in addition to at least one pigment, an organosilicon matrix. An organosilicon matrix is understood to be a coating matrix obtained from an organosilicon precursor material, which is also sometimes referred to as a "binder". Known organosilicon precursor materials include, for example, TEOS (tetraethyl orthosilicate), TMOS (tetramethyl orthosilicate) or their organomodified derivatives (m-TEOS, methyltriethyl orthosilicate, DMDEOS, dimethyldiethyl orthosilicate, phenyl triethyl orthosilicate, etc.). Silicones and polysiloxanes are also considered possible components of organosilicon binders within the scope of this disclosure. In particular, the organosilicon binder according to the present disclosure can particularly include a plurality of precursor materials. In particular, the binder can include a sol-gel component and a polysilsesquioxane component or a silicone resin component.

The coating is constructed in such a way that it is scratch-resistant itself, i.e. it has a scratch resistance of more than 7 N in a test according to DIN-ISO 1518-1 as a single layer on a glass or glass-ceramic substrate. have

Generally, within the scope of this disclosure, a layer of material applied to a substrate by a coating step is referred to as a coating or layer.

Monolayers are understood within the scope of the present disclosure to be coatings or layers of the same composition. Here, the coating can be applied in multiple coating steps or in a single coating step. For example, a monolayer within the scope of the present disclosure can also be obtained by two or more successive coating steps, such as double printing. This can be advantageous, for example, in the case of coatings with very low hiding properties, for which only low layer thicknesses can be obtained in a single coating step, for example screen printing. Such a coating can also be interpreted as containing two partial layers of the same composition. In this case, it is advantageous to carry out at least one or even more further coating steps after the first coating step, for example the first printing, so that a sufficiently thick overall coating is obtained. be able to. Here, it is also possible, but not absolutely necessary, to carry out intermediate steps after the coating process, such as, for example, heat setting of the preceding coating.

In contrast to a single layer, within the scope of the present disclosure there are multiple layers (or coatings) comprising material layers with different compositions, for example with regard to the type of pigments used or the type of binder used. A binder may also be referred to within the scope of this disclosure as a binder phase or matrix, and this is particularly the case when referring to a cured coating rather than a paste.

The coatings of the invention on glass or glass-ceramic plates also exhibit very good durability in oil tests.

In the scope of the present disclosure, an oil test is understood to be a test for determining the permeability of a coating film to oil. The visibility of fluids that penetrate a coating and are then visible through the coated substrate is a difficult problem, especially in the case of coatings containing effect pigments, for example. This is because it has been found that depending on the detailed composition of the coating, especially if the coating contains effect pigments, the penetration of the fluid may only be partially visible at certain angles. This is different from the case, for example, of coatings which are formed as pure "extension coatings", ie coatings which contain no or only a small amount of effect pigments. In this case, for example, when water penetrates into the pores of the coating, the color appears darker due to the filling of the pores, making it very easily visible.

Therefore, the present inventors developed the above-mentioned test method to test the sealing properties of the coating film, and in this method, an oil mixed with a dye as described above is used. If the sealing properties of the coating are not sufficient, the oil, i.e. together with this added dye, will penetrate into the pores of the coating and will also visually cause damage on the "other side", i.e. the side of the coating adjacent to the substrate. That is, it can be perceived in the form of a color change carried out by chromaticity measurements before and after loading with colored oil. Here, the chromaticity change ΔE is less than or equal to 2, preferably even smaller, particularly preferably ie imperceptible, in the coating according to the embodiment. The coating is therefore considered to be fully occlusive.

Such an embodiment in which the monolayer is both scratch resistant and impermeable was hitherto unknown. Conventionally, it has been thought that at least two coatings with different compositions are required depending on, for example, pigment and binder contents and baking conditions. The first coating placed directly on the substrate is porous, especially due to baking at high temperatures, and the second coating placed on the first coating is occlusive and its In this case, in particular, thermal seizure at high temperatures of 300° C. or above 350° C. was avoided. Such prior art known glasses or glass-ceramic plates are thus so-called two-layer systems in which the first and second coatings are characterized with respect to their composition, baking conditions and, if desired, the color impression obtained. Contains coatings that must be compatible with each other. Only in this way was it possible to ensure sufficient scratch resistance and at the same time sufficient sealing properties and sufficient mechanical strength of the glass or glass-ceramic plate under the conditions of use.

The inventors speculate that the scuff resistance as well as sealing properties of the monolayers of the present disclosure are due to the particular composition of the binder used. Thus, the coating used in the production of glass or glass-ceramic plates according to embodiments includes a binder that includes at least two organosilicon precursors or precursors. One organosilicon precursor is a silicone resin, especially a commercially available silicone resin, and the other organosilicon precursor is a sol-gel hydrolysis product. In addition to the binder, the coating further comprises at least one pigment.

This configuration is very advantageous. Because it is very possible to adjust the advantageous properties of pigment coatings with not too strong but sufficient adhesion strength by using sol-gel hydrolysis products of organosilicon compounds or mixtures of organosilicon compounds. This is because it is easy to use. However, as already indicated, such coatings are not suitable for forming a single layer on glass or glass-ceramic substrates for use as a backside or bottom coat. Because these layers are either too baked and therefore too porous, they do not exhibit self-sealing properties (i.e., very good oil resistance according to the present disclosure) or they dry without baking. However, this is because the temperature stability is not sufficient. This is because when a cooking appliance equipped with this is later operated, ie under a heat load, baking occurs and the sealing properties of the coating deteriorate over time. Furthermore, a coating film that has not been baked does not have excellent adhesion strength and therefore does not have sufficient scratch resistance.

However, it has now become surprisingly easy to provide glass or glass-ceramic plates with coatings that already have scratch resistance and sealing properties when implemented as a single layer.

According to one embodiment of the glass or glass-ceramic plate, the bending strength measured in accordance with EN 1288-5 with the double ring method in the glass or glass-ceramic plate is (measured as the arithmetic mean of) at least 140 MPa, preferably at most 250 MPa. This advantageously supports the mechanical stability of the glass or glass-ceramic plate. According to one embodiment, the glass or glass-ceramic plate has a 5% fractile with a bending strength of at least 100 MPa, advantageously at least 18 samples are used to determine the 5% fractile.

According to one embodiment, the impact resistance measured in a ball drop test according to UL 858 in a glass or glass-ceramic plate is at least 45 cm, advantageously at least 60 cm, advantageously at least 70 cm, advantageously at least 80 cm, particularly preferably at least 90 cm, where the impact resistance is for a coating arranged on the underside of the glass or glass-ceramic plate. Desired. Furthermore, according to one embodiment, the impact resistance measured in the ball drop test according to UL 858 in the glass or glass-ceramic plate is at least 35 cm, advantageously at least 40 cm, particularly preferably at least 45 cm or more. Also, for the measurement of impact resistance, the coating is placed on the lower side of the sample, i.e. the impact (or ball drop in the test) causes a load on the upper side of the sample or glass or glass-ceramic plate. The coating according to the embodiment is arranged on the opposite side of the sample/glass or glass-ceramic plate.

As already explained, the lower side of a glass or glass-ceramic plate is understood to be the side of the plate that faces away from the operator/viewer/user during operational use of the plate. For example, it is possible and even preferred to provide the lower side with projections, since in this way a particularly high strength of the plate, in particular also also impact resistance, can be set. However, it may also be provided to smooth both sides of the plate, since this makes it easier, in particular, to integrate the display element below the plate as part of the control element of the equipment equipped with the plate. This is to make it easier.

According to a further embodiment of the glass or glass-ceramic plate, the glass or glass-ceramic plate has, in the area where the coating is arranged, less than 0.08%, preferably less than 0.08%, measured according to DIN 5036 Part 1. It has a light transmission of less than 0.04%, particularly preferably less than 0.02%. The light transmission data preferably relates to areas where only the coating according to the embodiment is arranged on the glass or glass-ceramic substrate.

Therefore, in other words, the coating film is formed to be substantially opaque or concealable.

This can be advantageously assisted by a suitable ratio of pigment to binder in the coating. According to one embodiment of the glass or glass-ceramic plate, the ratio of pigment to binder in the coating is between 0.8 and 1.3, preferably between 1:1 and 1:2, respectively based on the weight proportions. 5, particularly preferably 1:1.3 to 1:2. In this way, a good hiding effect of the coating is advantageously ensured. Furthermore, it is also possible in this way to design the glass or glass-ceramic plate in such a way that it provides high strength and at the same time sufficient adhesion strength of the coating.

When referring to a "pigment to binder" ratio within the scope of this disclosure, the total pigment contained in the coating is always intended herein. Pigments are here understood to mean colored bodies containing particles, in particular inorganic colored bodies, preferably ceramic, ie inorganic non-metallic colored bodies. For example, it is possible and necessary for the coating to contain more than one pigment, e.g., pigments having different colors or shades of color, in order to adjust a particular color and/or one of the other properties of the coating. It may be. In this case, the numerical value of the pigment/binder ratio is based on the total amount of pigments contained in the coating film, that is, the total pigment ratio.

According to a further embodiment, the coating comprises effect pigments, the proportion of effect pigments relative to the total pigment proportion being between 50% and 100% by weight, preferably between 70% and 100% by weight, particularly preferably 88% by weight. ~98% by weight.

The construction of coatings containing at least one effect pigment is usually carried out in order to adjust a particular appearance ("metallic coating"). However, it has been found that effect pigments can also perform other functions within the coating. This is because the generally flaky formation of many effect pigments, such as so-called pearlescent pigments, can additionally support the formation of advantageous properties of the coating, such as high abrasion resistance. It may therefore advantageously be provided that the proportion of effect pigments relative to the total pigment proportion is not too low, for example at least 50% by weight, advantageously at least 70% by weight, particularly preferably at least 88% by weight.

In general, it is possible for a coating as a colored body - or even a coating as an "effect body" in the special case of effect pigments - to contain only one effect pigment, so that the proportion of effect pigments relative to the total pigment proportion is The proportion can also be 100% by weight. However, it may be advantageous and preferred for its content to be lower, for example only 98% by weight. This may be particularly advantageous if the effect pigment itself is not colored, for example a pure "silver-white" pearlescent pigment. In this case, setting a sufficiently high optical density of the coating - in other words making the coating "hidden" - would be achievable only by increasing the layer thickness very thickly. It may therefore be advantageous to further add at least one further pigment, or optionally also several other pigments, which develops color by absorption and/or scattering, in order to increase the hiding effect of the coating. It may also be advantageous for the coating to contain, in addition to the effect pigment, at least one further pigment, in particular an absorption pigment or a white pigment, in order to achieve a particular color impression, in particular a deep color. .

It is of course also possible for the coating to be free of effect pigments.

As described above, the coating film according to the embodiment is formed as a single layer, and is already formed as a single layer so as to have both scratch resistance and sealing properties.

The fact that the coating is formed as a single layer does not mean that the glass or glass-ceramic plate according to the embodiments must contain only a single coating on the surface of the plate on which the coating is also arranged. . It is possible, and may be preferred for various reasons, for one or more further coatings to be disposed on that surface. However, the further coating does not determine the properties of the first coating and may be applied, for example, as a functional layer for the operation of an electronic component or the like. In this case, the advantageous properties of the coating are those areas of the glass or glass-ceramic plate where no further coating is arranged between the substrate and the coating or on the coating itself, but only the coating itself. can be determined.

In this way, the present inventors have for the first time opened up the possibility of providing a coating film suitable as a bottom or backside coat, even if it is a single layer. As explained, this is advantageously made possible by the special construction of the coating such that it contains two organosilicon precursors. Here, the present inventors assume that the addition of silicone resin plays a role in ensuring sufficient sealing performance.

Accordingly, according to one aspect, the invention also provides a method of manufacturing a glass or glass-ceramic plate according to an embodiment of the disclosure, comprising:
- providing a glass or glass-ceramic substrate;
- providing a coating comprising a pigment and a binder comprising two organosilicon precursors, wherein one organosilicon precursor is a silicone resin and the other organosilicon precursor is a sol-gel hydrolysis product; a process,
- applying the coating to one side of a glass or glass-ceramic substrate to form a coating, preferably by a printing method;
- applying the coating at a temperature of at least 200°C and at most 400°C for at least 10 minutes and at most 120 minutes, preferably at a temperature of at least 250°C and at most 330°C for at least 30 minutes and at most 90 minutes, especially at most baking at a temperature of at least 300° C. and at most 320° C. for at least 30 minutes and at most 60 minutes.

Such a method not only allows the production of glass or glass-ceramic plates according to the embodiments, but also provides the advantage of easier process control. In particular, according to the method of the present disclosure, since a single layer is now applied, ie, there is no need to keep a stock of various pastes for logistics purposes, the logistics costs associated with production are significantly reduced. and, if the desired shade of the coating is very light, in some cases from above, i.e. through the substrate, by applying a darker but sealing layer on top of the first light-colored coating. There is no need to consider changes in chromaticity. This is because, with this very combination, it has previously happened that if the first layer was not opaque enough or was transparent, the darker backprinting could change the chromaticity of the first coating. Because I got it.

According to a further aspect of the disclosure, the invention also relates to a glass or glass ceramic plate produced or at least producible by the method according to an embodiment.

The table below shows by way of example the composition of three coatings or pastes from which glass or glass-ceramic plates according to embodiments are obtained.

The composition of an exemplary paste according to the table above includes as solid components, in addition to the filler, here a plurality of pearlescent pigments, a white pigment and graphite as a dark component. These components, whose proportions are variable, are used here to achieve a particularly favorable chromaticity. It is therefore also possible to use other pearlescent pigments or only one. As a white pigment, for example TiO ₂ can be used. General compositional ranges of coatings or pastes for producing glass or glass-ceramic plates according to embodiments are summarized below:

For pigments, ie white pigments, pearlescent pigments and other pigments, including in particular absorption pigments such as spinel, ie particularly high temperature-stable oxide pigments, the respective totals are given. Thus, the paste or coating can contain only one or several pearlescent pigments, in which case the sum of all pearlescent pigments contained in the coating is at most 53.9% by weight. . The coating can therefore contain only one or several white pigments, the sum of all white pigments being within the aforementioned limits and the same for the other pigments.

Furthermore, other effect pigments may be included in addition to the pearlescent pigments. However, the sum of pearlescent pigments and other effect pigments must not exceed 53.9% by weight. Other effect pigments can be based on, for example, Al ₂ O ₃ , SiO ₂ or borosilicate glass flakes and can have different coatings. By using such effect pigments, it is possible to achieve both a color impression and further effects, such as glitter or metallic effects, for example.

An example of a composition for producing a sol-gel hydrolysis product is shown in the table below:

Silane was charged and p-toluenesulfonic acid dissolved in water was added. After stirring for 1 hour, the resulting ethanol was distilled off.

The present invention will be further explained below with reference to the drawings.

FIG. 3 shows a scanning electron microscope image of a glass or glass ceramic plate containing a coating film. FIG. 2 is a diagram showing a photograph of a glass or glass ceramic plate for explaining oil resistance. It is a figure which shows the photograph of the glass or glass ceramic plate for demonstrating abrasion resistance.

FIG. 1a shows a scanning electron microscope image of a prior art glass or glass-ceramic plate 10 comprising a coating 2 configured as a two-layer system. The glass or glass-ceramic plate 10 is here designed as a glass-ceramic plate, that is to say it comprises a substrate 1 comprising a glass-ceramic in this case. As can be clearly seen, the coating 2 comprises two different layers (or partial layers) 22, 21, one layer 21, which is arranged towards the substrate 2, is a coloring layer and the other Layer 22 is arranged on first layer 21 . In FIG. 1a, a boundary line (or interface) 23 between a first layer 21 and a second layer 22 is schematically drawn. As can be seen from the scanning electron microscope image in FIG. 1a, the second sealing layer 22 has a different microstructure, for example a matrix 221 that is more granular than the matrix 211 of the layer 21.

In contrast, the glass or glass-ceramic plate 10 according to an embodiment of the disclosure is here likewise formed as a glass-ceramic plate, i.e. a glass-ceramic plate comprising a substrate 1 comprising a glass-ceramic and a coating 2. It is formed as a plate. The coating 2 is here constructed as a double layer in the form of two copies of a paste with the same composition, so that a coating correspondingly comprises two partial layers. As explained, such a coating 2 is referred to as a monolayer within the scope of the present disclosure, since the two partial layers forming it have the same composition. Here, the two partial layers of the same composition have very good adhesion to each other due to the same composition, and are difficult to distinguish in the scanning electron microscope image of FIG. 1b.

In contrast to this is a two-layer system of different composition, as illustrated in FIG. 1a, in which there are layers 21 and 22.

FIG. 2 shows a photographic image of a sample of glass or glass-ceramic plate 10 to illustrate oil resistance. In figure 2b the back side of the coating 2 of a different plate 10 is shown, and in figure 2a the same plate 10 can be seen, but here the plate is oriented with the substrate 1 facing upwards, i.e. The photo was taken with the camera facing towards the camera.

In Figure 2b, the residue of the colored oil is still clearly visible on the back side of the specimen (bluish stain, dark shadow in the monochrome photograph). In Figure 2a, the samples are shown in the same order as in the photo in Figure 2a, but there is a clear difference in the appearance of the oil here: the sample on the left has a clearly visible stain; , which means a correspondingly large change in chromaticity, but the stain on the central sample is very difficult to see. In the sample on the far right, in contrast to the other two samples, the stain is no longer visible through the substrate. This can also be evidenced by corresponding measurements of chromaticity in comparison between treated and untreated, where the chromaticity difference ΔE is found to be less than 2, and here even only 0.22. There is.

FIG. 3 shows two photographic images of test specimens subjected to a scratch test, in particular DIN-ISO 1518-1. For this purpose, the test chip is pulled with a predetermined contact (defined by the contact force) on the surface of the coating, particularly preferably in the area where only the coating is applied to the substrate.

This test, within the scope of this disclosure,
- The test is considered to have passed if - the trace of the test needle is not visible to the extent that it is a nuisance when viewed from above, i.e. through the substrate, or - no peeling of the coating has occurred.

It is advantageous that the trace of the test needle is not visible from above, ie through the substrate. This is particularly important in coatings containing effect pigments. This is because, as can be seen from the test traces in Figure 3a, in the case of coatings with a so-called "metallic effect", even before the coating has visibly peeled off, there is a layer that is visually perceptible through the substrate. This is because damage may occur. The inventors believe that this can be due to a "squashing" of the effect pigment, and therefore, in the visual impression through the substrate, there is a difference between the unloaded coating and the areas of the coating that bear test marks. It assumes that the difference is perceptible. However, in the case of the plate according to the embodiment, unlike the prior art plate, this occurs only after applying a load of 7 N or more, if at all.

The coating therefore has a resistance of more than 7 N in the test according to DIN-ISO 1518-1, preferably at most 30 N, in the areas of the glass or glass-ceramic plate where only the coating is arranged on the glass or glass-ceramic substrate. Scratch resistance.

Advantageously, the scratch resistance may be greater than 16N, for example up to 17N or even up to 18N, especially when delamination is taken into account. According to one embodiment, it is therefore possible to have a scratch resistance of 16 N or more, ie according to this embodiment no delamination occurs at the mentioned loads in the scratch test.

However, too high abrasion resistance correlates with too good adhesion of the layers, which can lead to a significant reduction in the mechanical durability of the plate and is therefore turned away from the user. This is disadvantageous for coatings that are expected to be placed on the surface of a plate (bottom coat or back coat). According to one embodiment, therefore, the scratch resistance of the coating is at most 30N.

Here, within the scope of the present disclosure, the expression "in the region of the glass or glass-ceramic plate where only the coating is arranged on the glass or glass-ceramic substrate" generally means in this case It is understood to refer to the surface. The other side of the plate may additionally be provided with another coating, for example a ceramic decoration for cooking zone markings. However, as will be readily understood by those skilled in the art, it is only the adhesion of the coating to the substrate or its inherent sealing properties that are important for the scratch resistance and also the oil resistance of the coating. Naturally, there is no further coating, such as a top decoration, which is optionally placed on the opposite side of the plate.

1 Glass or glass-ceramic substrate 10 Glass or glass-ceramic plate 2 Coating film 21, 22 Partial layer of 2 23 Border/interface between 21, 22 211 Matrix of 21, binder phase 221 Matrix of 22, binder phase

Claims (9)

A glass or glass-ceramic plate comprising a glass or glass-ceramic substrate and a coating comprising an organosilicon matrix and a pigment disposed on at least one side of the glass or glass-ceramic substrate, the coating comprising: has a thickness of at least 10 .mu.m, advantageously at most 80 .mu.m, said coating being of said glass or glass-ceramic plate in those areas where only said coating is arranged on said glass or glass-ceramic substrate. , a scratch resistance of more than 7 N, preferably at most 30 N, in a test according to DIN-ISO 1518-1 and less than 1 determined as a chromaticity change ΔE when measured through said glass or glass-ceramic substrate, preferably less than 0.5, particularly preferably less than 0.3, very particularly preferably less than 0.2 and most preferably less than 0.1, wherein said chromaticity change ΔE is L ^* a ^* b ^* The following formula in color system:

Glass or glass-ceramic plates, given by. having a bending strength of at least 140 MPa, preferably at most 250 MPa, determined by the double ring method according to EN 1288-5, determined as the arithmetic mean value across the samples of at least two samples; A glass or glass ceramic plate according to claim 1. at least 45 cm, advantageously at least 60 cm, advantageously at least 70 cm, advantageously at least 80 cm, particularly preferably at least 90 cm, wherein the impact resistance is determined for a coating arranged on the underside of the glass or glass-ceramic plate. The glass or glass ceramic plate according to 2. The glass or glass-ceramic plate has a content of less than 0.08%, preferably less than 0.04%, particularly preferably less than 0.04%, measured according to DIN 5036 Part 1, in the area where the coating is arranged. 4. Glass or glass-ceramic plate according to claim 1, having a light transmission of less than 0.02%. The ratio of pigment to binder in the coating is in each case based on weight proportions from 1:0.8 to 1:3, advantageously from 1:1 to 1:2.5, particularly preferably from 1:1.3. Glass or glass-ceramic plate according to any one of claims 1 to 4, wherein the ratio is ˜1:2. Said coating film comprises effect pigments, the proportion of said effect pigments relative to the total pigment proportion being between 50% and 100% by weight, preferably between 70% and 100% by weight, particularly preferably between 88% and 98% by weight. A glass or glass ceramic plate according to any one of claims 1 to 5. A method for producing a glass or glass-ceramic plate, in particular a glass or glass-ceramic plate according to any one of claims 1 to 6, comprising:
- providing a glass or glass-ceramic substrate;
- providing a coating comprising a pigment and a binder comprising two organosilicon precursors, wherein one organosilicon precursor is a silicone resin and the other organosilicon precursor is a sol-gel hydrolysis product; a process,
- applying said coating to one side of said glass or glass-ceramic substrate to form a coating, preferably by a printing method;
- the coating is applied at a temperature of at least 200° C. and at most 400° C. for at least 10 minutes, at most 120 minutes, preferably at a temperature of at least 250° C. and at most 330° C. for at least 30 minutes, at most 90 minutes, especially at most baking at a temperature of at least 300° C. and at most 320° C. for at least 30 minutes and at most 60 minutes. The ratio of sol-gel hydrolysis product to silicone resin in the coating is from 1:0.2 to 1:0.02, preferably from 1:0.09 to 1:0.035, based on weight. 8. The method of claim 7, wherein: Glass or glass-ceramic plate according to any one of claims 1 to 6, produced or producible by the method according to claim 7 or 8.